Hydrochloric Acid → ethyl (2E,4E)-5-(1-hydroxy-2,6,6-trimethyl-4-oxocyclohex-2-en-1-yl)-3-(trifluoromethyl)penta-2,4-dienoate

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Reaction Steps

Ethyl (2E,4E)-5-(8-hydroxy-2,3,7,9,9-pentamethyl-1,4-dioxaspiro[4.5]dec-6-en-8-yl)-3-(trifluoromethyl)penta-2,4-dienoate (150 mg, 0.36 mmol) was dissolved in acetone (5 ml) under argon in a round-bottom flask, and 10% strength hydrochloric acid was added. The resulting reaction solution was stirred at room temperature for 40 minutes, and water was then added. After removing acetone under reduced pressure, the aqueous phase was extracted repeatedly with dichloromethane. The combined organic phases were dried over magnesium sulfate, filtered and concentrated under reduced pressure. By column chromatography purification of the resulting crude product (ethyl acetate/heptane gradient), ethyl (2E,4E)-5-(1-hydroxy-2,6,6-trimethyl-4-oxocyclohex-2-en-1-yl)-3-(trifluoromethyl)penta-2,4-dienoate (80 mg, 61% of theory) was obtained in the form of a colorless oil. 1H-NMR (400 MHz, CDCl3 δ, ppm) 7.55 (d, 1H), 6.37 (d, 1H), 6.33 (s, 1H), 5.97 (s, 1H), 4.25 (q, 2H), 2.47 (d, 1H), 2.34 (d, 1H), 1.92 (s, 3H), 1.90 (br. s, 1H, OH), 1.33 (t, 3H), 1.11 (s, 3H), 1.02 (s, 3H).

Provenance & Evidence